ADVICE PLEASE: On a annoying RAID issue.

[Steve Modica]

[Chris Simpson] “Now here’s my simple maths, forgive me if I’m too simple, 12 streams of Pro Res LT (@85Mb/s or 10.7MB/s). Or 1027.2 Mb/s or 128MB/s, the AJA system test I’m getting average write speeds around 700MB/s and read speeds around 420MB/s, the pipe, if my simple math/understanding is right, ought to be wide enough. Which leaves me puzzling over the inconsistent speed over the course of the AJA test.”

Hi Chris

This sort of math doesn’t hold up with raid controllers. Their performance on a drag race test like AJA doesn’t equate to their performance when running 10 streams of something low bandwidth. It’s also true that you need to have fairly reliable, stable, low latency response through the entire run, not just an overall number that gives you good bandwidth. For example, your raid could glitch for half a second during the test and still pump out 750MB/sec, but you would certainly drop frames during that glitch. (We’ve profiled older variants of Areca and seen this behavior. I’ve not looked at the newer cards).

Have you worked with Areca support to see if they can help improve this number? There are a number of vendors (like Small Tree and Maxx) that sell systems that have been profiled and tuned to do this kind of work off the shelf.

Steve

Steve Modica
CTO, Small Tree Communications

[Chris Simpson]

Thanks for the reply Steve, I did not think my simple math really would be how it works, although I did feel the higher the number the more likely it would be indicative of it’s capability, in much the same way as racecar horsepower is not the whole story on top speed, but it’s fair to say you’d expect a corvette motor to give a car a higher top speed than a motor out a Hyundai.

And moreover historically this mac pro and enclosure has given 750+ on both write and read, and a nearly flat trace.

I was hoping that someone might recognise this trace for what it is, it’s distinctive and nearly always the same, the earth quake on read speeds and a distinct kink in write. Although (maybe being too simple again) i feel the earth quake on read trace is where the heart of the problem is.

As to vendors I’m based in the UK, the specialist vendor who I have worked with is very good, and replaced the first highpoint card at his expense, always available at the end of a phone, and in every way superb but i feel has run out of ideas on this one.

I need a sort of a diagnostic service, which needs to work, via email and/or something like Teamviewer. While more IT savvy than everyone I know, I’m an editor, and by no measure an IT expert.

[Jon Schilling]

Chris,

I’m with Proavio/Enhance Technologies. While it’s good to see that you went with the Areca 1882x card, we do not recommend using WD Caviar green drives in our arrays and using them would lend itself to poor performance. I’m going to check with our lead technician, Luis Rodriguez & I’ll have him follow up. You are of course free to call or email us as well.

Jonathan Schilling
Vertical Sales Manager
Proavio
12221 Florence Ave.
Santa Fe Springs, CA 90670
Dir: 562-777-3498
Main: 562-777-3488 X106
Fax: 562-777-3499
Email: jon@proavio.com

See our forum: https://forums.creativecow.net/proavio

[Steve Modica]

[Chris Simpson] “I did feel the higher the number the more likely it would be indicative of it’s capability”

This is usually not the case. In fact, I’ve found that some of the fastest drag race cards are the worst multistream performers. Engineers optimize for the big marketing number at the expense of a more random looking load. When we first got into the storage space, we were testing one vendors card (the fastest we were aware of) and it could not push one Pro Res stream reliably. It glitched to often.

I would call areca on this. I know they have tuning things for their cards. I know they’ve been working on that sort of performance. They should be able to help.

Steve

Steve Modica
CTO, Small Tree Communications

[Chris Simpson]

Jon,

I was surprised when I took the drives out to find they were caviar green, I knew they were WD, from raid web gui or disk utility, but was surprised as it was not my decision (don’t put a lot if stock, in the green version of anything, be it wind farms that dont work, or electric cars, how green is that charge generated, or those exotic battery materials) but it was the raid vendor’s decision and to be fair they have worked well for a couple years, until about 4-5mths ago, when the 2nd highpoint card was removed (and I’m beginning to wonder if that may in fact by fine), so it begs the question what drives would be happy to see in proavio raid, I may as well upgrade to 2tb drives, so caviar black (Shane Ross suggested in the FCP forum)? But I’ve been reading around today, and read that there may or may not depending on who you read on the web, a TLER issue with consumer WD so should go RE4 but not RE4GP, or hitachi ultrastar, or maybe maybe not deskstar, or seagate not barracuda, but enterprise constellation, etc, I read and read and there’s a plethora of recommendations, negative reports and technical jargon that washes back & forth, over the plain “I’m the driver, not the mechanic” in me.

So if you have an opinion, as a rep of the enclosure manufacturer (and i appreciate other drives are available), what drives would you reccommend from experience and customer feedback (I’ll email if it’s at all tricky)?

Steve,

Areca has a US office for its US customers and a worldwide one in Taiwan, for the rest, according to tge website, while I’m happy to contact either, timezones (12hrs from the UK) and potentially (although i doubt it) a language barrier (Taiwan) at least make it difficult to call Areca, I’ll email though.

Moreover thank you both for your time.

I’m feeling it isn’t the card, problems pre date it, although I appreciate tuning it, might help, i’m still thinking its either drive related, or (at a stretch) mac pro related (although the internal raid seems fairly quick and fairly consistent on test). It’s just annoying, I’m sure there’s a rapid and reliable RAID trapped trying to get back out for business but its a proving expensive issue to work through!

[Luis Rodriguez]

Chris, that does not look good. Apart from using Green drives which are not recommended for RAID use there could be something else causing the peformance issues.

Which PCI-e slot is the Areca card installed in?

Drop me an email, I have a few tweaks that may improve your situation. For the moment I would recommend creating two 4-drive RAID sets and volumes. Compare the performance between the two volumes and see if the numbers are consistent. From there we can try to isolate the issue and determine if we have a potential problem with one or more drives.

Luis Rodriguez
Proavio
12221 Florence Ave.
Santa Fe Springs, CA 90670
Dir: 562-777-3498
Main: 562-777-3488 X109
Fax: 562-777-3499
Email: luis@proavio.com

[Chris Simpson]

Hi Luis,

Thats very kind of you. I will be in touch. I’m happy to replace these green drives, should it prove to be the issue in the end I was intending to upgrade from 1TB drives to 2TB soon anyway.

It’s in slot 4, this is an old-ish Mac Pro 1,1, and to run x16 graphics in slot 1 and the raid card at full speed in x8, the only profile that fit is an alternate PCI express profile of 16, 1, 1, 8. My vendor was always keener to run the raid controller in slot 2, but there just were not the lane capacity, I’d be happier myself as in slot 4 is under internal drive bays 3 & 4, which are often quite warm.

It’s a very long public holiday weekend in the UK, (our Queen’s diamond jubilee), not that it matters, save for an opportunity (and unfortunately) I have too large a project to move and needs to be completed, and of course, it’s sat on the RAID, and although I’ll have to soldier on, it should be complete by Sunday night. If it’s alright I’ll email Monday. If you don’t mind.

Thanks again. And to Steve & Jon. A great place The Cow!